Laminated safety glass and plastic therefor



Patented Apr. 7, 1942l UNITEDv STATES PATl-:N'ry OFFICE y y 2,219,145- LAMINATED smn'il'yngllszs AND PLASTIC 'Joseph D. Ryan,

Owens-Ford Glas corporation of Ohio Toledo, Ohio, assigner to Libbeys Company,

Toledo, Ohio, a

Application April 28, 1937, Serial No. 139,516

(Cl. dil-81.5)

6 Claims.

The present invention relates to laminated safety glass and more particularly to such a glass made with a synthetic resin plastic which has been plasticized with an aliphatic organic acid ester of an ether of diethylene glycol. 'I'his application corresponds to and is identical with my applicatim Serial No. 63,066, filed February Laminated safety glass has in the past ordinarily been made by bonding a layer of cellulose derivative plastic such as cellulose nitrate plastic or cellulose acetate plastic between two sheets of glass. These plastics have at least one common characteristic, namely, a tendency toward brittleness at the lower temperatures such as, for example, zero degrees F. l

Much work has been done in an attempt to produce a. plastic offering greater resistance to impact at all of the normal temperatures to` which the glass is ordinarily subjected, than the resistance oered by laminated glass made with the cellulose derivative plastics, and to particu-A larly increase the resistance yto impact of safety glass at the lower temperatures.

The synthetic resin field has been explored for some time with the hope of iinding or developing a new plastic suitable for safety glass manufacture and superior to cellulose derivative plastics for this purpose. Some attempts have been made to employ resins such as the acrylic acid ester type of resin, but such glass made with the acrylic acid ester as has come to my attention and which is offered on the open market, exhibits the same tendency toward brittleness at the lower temperatures as glass made from the cellulose derivatives. v

If the resinous product formed by the reaction of an aldehyde on partially or wholly hydrolyzed polymerized vinyl ester is plasticized with an aliphatic organic acid ester of an ether of diethylene glycol, a very satisfactory plastic is produced.' Included in the aliphatic organic acid esters of an ether of diethylene glycol are the ethyl ethers oi diethylene glycol esters, such `as ethyl ether of diethylene glycol acetate, ethyl resin; ,butylaldehyda giving -a so-called Butylvarv type of resin; or with an acetaldehyde, resulting in an Alvar type of resin. If preferred', the resinous products can be made simultaneously by polymerizing the monomeric vinyl compound and condensing with the selected aldehyde in a hydrolyzing medium, so that the-polymerization of the monomeric vinyl compound, hydrolysis of the polymer, and condensation with the aldehyde in these circumstances all. take place simultaneously.

It is pertinent to note that while these types oi' resins have the latent property o! giving a plastic offering much greater resistance to impact when bonded between glass sheets than is true with the cellulose derivative plastics, never- Vtheless this property can only be produced when generally less desirable than the cellulose derivative plastics. To emphasize this, plastic made by plasticizing the Butylvar type of resin with di;-

butyl tartrate, for example, which is a plasticizer for the resin, when bonded between glass sheets oiers no material resistance to impact at low .temperatures and is far inferior to laminated safety glass made with cellulose derivative plastics. Furthermore, there is not an adequate bond between the glass and such plastic at the lower temperatures.

On the other hand, by taking the very ,same resin and plasticizing it with proper amounts of an aliphatic organic acid ester of an ether oi' diethylene glycol, a very desirable plastic material is created and the resistance'to impact, when bonded between glass sheets, is far superior to such glass made with any of the cellulose derivative plastics. It thus obviously follows that the plasticizer employed is of vital importance to the results obtained. In accordance with this invention, the synthetic resin, whether it be of the Formvar, Alvar, or Butylvar type, is plasticized with approximately 50 parts by weight of the aliphatic organic acid ester of'anl ether of diethylene glycol. Of course the amount 4of plasticizer can be varied to suit or meet particular conditions or requirements as is well understood in the plastic art, but I have found that approximately 50 parts gives a plastic well suited for all of the varying temperature conditions to which laminated safety glass is normally subjected when in use in this country. Ordinarily, as the molecular weight of the plasticizer is increased, correspondingly lesser amounts of plasticizer may be used. 

